X Freeware

ffmpegX

http://homepage.mac.com/major4/

This is truly the Swiss Army knife or VLC of video encoding. Will take almost any format and convert it to something else.

HandBrake

http://handbrake.m0k.org/

This is the VLC of DVD video encoding. It will take a DVD and convert it into almost anything else. Handy for if you want to take your laptop on the road, but dont want to carry all your DVD's too.

iSquint

http://www.isquint.org/

This will convert almost any video to a video iPod compatible format. Universal as well

VLC

http://www.videolan.org/vlc/

The swiss army knife of video players. Can play almost everything except new WMVs. I use this instead of Quicktime Player 99% of the time. Required.